Templating Synthesis of Mesoporous Fe₃C‑Encapsulated Fe–N-Doped Carbon Hollow Nanospindles for Electrocatalysis

Developing cost-efficient alternatives to the noble metal catalysts toward oxygen reduction reaction (ORR) has attracted much attention. Herein, a kind of mesoporous hollow spindlelike Fe–N–C electrocatalysts with iron carbide nanoparticles encased in the N-doped graphitic layers has been synthesized by a novel “reactive hard template” strategy through the Fe³⁺-assisted polymerization of dopamine on the Fe₂O₃ cores and the following calcinations. The Fe₂O₃ nanospindles not only as the hard template guide the formation of well-defined shape and structure of the catalyst but also as the reactive template provide Fe reservoir to generate Fe₃C nanoparticles in the catalyst during the thermochemical process. The superiority in accessible active sites of Fe–N_<i>x</i> species, Fe₃C nanoparticles in graphenelike layers, and highly mesoporous hollow structure enables the catalysts to exhibit excellent ORR performances including high catalytic activity, outstanding long-term cycling stability, and good tolerance to methanol

Organized Molecular Interface-Induced Noncrystallizable Polymer Ultrathin Nanosheets with Ordered Chain Alignment

The orientation and state of organization of polymer chains play significant roles in determining the final properties and functions of these materials. Unlike most semicrystalline polymers, which have an inherent driving force toward crystallization, the means to control chain packing in noncrystallizable polymers is still restricted and remains a challenge. We report herein a 2D soft template-directed fabrication for ultrathin polyacrylamide nanosheets with a thickness as low as 3.5 nm and large dimensions (>20 μm). More importantly, the polymer chains in the nanosheets produced are well aligned with a clear interchain spacing. The formation of polymer nanosheets with ordered chain alignment was performed in a special solution containing a periodic sandwich structure of lamellar bilayer membranes and water layers that are hundreds of nanometers thick. It functions as a 2D orientation template to align the monomers in an orderly manner along the in-plane direction of the bimolecular membrane via hydrogen bonding

Conductive Carbon Network inside a Sulfur-Impregnated Carbon Sponge: A Bioinspired High-Performance Cathode for Li–S Battery

A highly conductive sulfur cathode is crucial for improving the kinetic performance of a Li–S battery. The encapsulation of sulfur in porous nanocarbons is expected to benefit the Li⁺ migration, yet the e^– conduction is still to be improved due to a low graphitization degree of a conventional carbon substrate, especially that pyrolyzed from carbohydrates or polymers. Aiming at facilitating the e^– conduction in the cathode, here we propose to use ketjen black, a highly graphitized nanocarbon building block to form a conductive network for electrons in a biomass-derived, hierarchically porous carbon sponge by a easily scaled-up approach at a low cost. The specifically designed carbon host ensures a high loading and good retention of active sulfur, while also provides a faster electron transmission to benefit the lithiation/delithiation kinetics of sulfur. The sulfur cathode prepared from the carbon network shows excellent cycling and rate performance in a Li–S battery, rendering its practicality for emerging energy storage opportunities such as grids or automobiles